Samlor
Samlor is a bi-pedal tricycle capable of carrying two passengers (five if you’re Thai) over short distances. All but gone from major centres, they still find much use in smaller provincial towns and a few suburbs of major cities.
Samlors are inexpensive, as low a 1 baht per minute on average, though these guys work hard so I rarely bother bargaining with them. The drivers speak little English so you may need to be patient with explanations if you aren’t going to a specific landmark. A map with Thai and English on it is ideal.
If you venture into the small cities, a 100 baht for an hour of touring in a Samlor is a great way to experience Thailand at a leisurely pace.